Electrical plug-and-socket connections



Dec. 6, 1966 L. G. M. PAYNE ETAL 3,

ELECTRICAL PLUG-AND-SOCKET CONNECTIONS 2 Sheets-Sheet 1 Filed June 15,1964 Dec. 6, 1966 L. 3. M. PAYNE ETAL 3,

ELECTRICAL PLUG-AND-SOCKET CONNECTIONS 2 Sheets-Sheet 2 Filed June 15,1964 United States Patent ()fiiice 3,296,641 Patented Dec. 6, 19663,290,641 ELECTRICAL PLUG-AND-SOCKET CONNECTIUNS Leslie George MountjoyPayne and Edward Thomas Buckeridge, both N ewbridge Works, Somerset,Bath, England Filed June 15, 1964, Ser. No. 375,152 Claims priority,application Great Britain, July 10, 1963, 27,306/ 63 1 Claim. (Cl.339266) This invention relates to improvements in electricalplug-and-socket connections particularly for time switches, and has forits primary object to reduce contact resistance between plug and socketthus reducing the heat generated in the connection and avoiding too higha proportion concentrating in the plug part of the connection. Such aconcentration with the attendant poor dispersion of heat has manifestdisadvantages, and this is particularly so when the plug extends rigidlyfrom an instrument or the like which is plugged into the socket.

The invention is particularly applicable to, but not limited to,plug-and-socket connections for electric time switches fitted with apair of rigidly projecting plugs for insertion in a pair of sockets(load and line) in an electrical circuit for automatically controllingthe current supply to an electricity consuming point at predeterminedtimes. In such an application the invention minimises the amount of heatconveyed by the plugs into the time switch mechanism. With high ratedloads especially, e.g. of over 60 amps. it is highly desirable to avoidover-heating of the time switch.

According to the said invention an electrical plug-andsocket connectionincludes a metal socket block for the reception of a plug, said blockhaving a socket part containing a socket hole, and a main bodyintegrally extending from said socket part and containing a first slotlying in a plane parallel to the axis of said hole cutting into thelatter and opening out at one face of the said body to form alongitudinally split socket, a second slot in said main body not cuttinginto the socket hole thereby forming a clamping tongue in the main body,in combination with a bore in said main body parallel to the axis of thesocket hole, and intersected by the second slot, said bore containing aclamping pin adapted by rotation to fiex the said clamping tongue andclose the socket into a plug gripping condition.

By this means the two-piece plug-and-socket connection, from the pointof view of heat dispersion, becomes the equivalent of an integral solidmass comprising the metal socket block together with the solidly grippedplug, and heat generated at the connection is more readily dissipated bysuch a larger mass than simple plug-in arrangements, being dispersed toa greater extent through the socket block structure which usuallyincludes an extra block mass carrying lead-in attachment devices and aninsulated encasement therearound. Also, the plug is firmly retainedmechanically in the socket with no posssibility of vibrating loose orworking loose by the continual unplugging and -re-plugging during use ofthe connection.

In the aforesaid application of the invention to a plug-and-socketconnection for a time switch, there is usually employed an insulatedcasing having an integrally moulded part containing a pair of recessesfor the reception of a brass or other socket block in each, the twoblocks being each formed with the socket part of the connection to takethe respective complemental plugs of the time switch; each mouldedrecess is made with a lead-in cable entry hole opening thereinto andleading from a hole on the exterior of the casing through which theelectrical cable for the socket can be introduced and the conductor wireclamped in the brass block by terminal screws. The present invention isuseful for such an application, the recesses in the moulded part beingshaped so as to correspond with the configuration of the metal socketblock of the invention.

An embodiment of the invention will be described by way of example Withthe aid of the accompanying drawings wherein:

FIGURE 1 is a perspective view of a plug-and-socket connection accordingto the invention, with the plug and a clamping pin removed;

FIGURE 2 is a plan view of the socket;

FIGURE 3 is a section on IIIIII of FIGURE 2;

FIGURE 4 is a section on IVIV of FIGURE 2;

FIGURE 5 is a section on VV of FIGURE 2;

FIGURE 6 shows part of the casing and lid of an electric time switch inwhich there is shown the socket part of a plug-and-socket connectionaccording to the invention; and

FIGURE 7 is a section through VIIVII of FIG- URE 6.

Like numerals of reference indicate the same or corresponding parts inthe several views.

A brass socket block designated generally 1 has a socket part 2containing a socket hole 3 extending only partly therethrough andpreferably cylindrical, say about two-thirds the length of the saidsocket part from top to bottom, so as to leave the bottom solid. Thissocket part 2 is mainly cylindrical on its external surface and is alateral projection from an integral main body designated generally bythe numeral 4 of similar length thereto, the top and bottom faces of thesocket part and main body being co-planar. The reference to top andbottom assumes, for convenience of description, that the block isdisposed with the face which contains the socket entry on top in ahorizontal plane, but it is to be understood that the direction of theplug-in operation may be vertical, horizontal, or inclined to thevertical. The main body 4 is conveniently of T-section, the top bar ofthe T at 5 and 6 (FIGURES 1 and 2) being wider laterally than thecylindrical socket part 2, the leg 7 of the T extending in a directionaway from the latter, and being offset from the axis of the socket hole3. Thus, one end 6 of the T-crossbar forms a longitudinal projectingflange with respect to the socket part 2, and the other 5 a shorterflange.

Cut longitudinally through the main body 4 from its top face is a firstslot 8 lying in a plane substantially parallel to the axis of the sockethole 3, slightly spaced thereform, and extending downwardly to a depthroughly equal to the length of the socket hole. The plane of the saidslot 8 may coincide with the axis of the socket hole, and thedescription substantially parallel is intended to cover this. This firstslot 8 cuts into the hole 3 and opens out at the vertical face 9 of thebody formed by the base of the leg 7 of the T-section at a point 10(FIGURES 1 and 5) away from the bottom thereof, thus forming alongitudinaly split socket for the reception of the plug 11 (FIGURE 1).The plug is preferably solid and unsplit longitudinally. A second slot12 is cut in the main body 4 also leading from its top face and lying ina plane substantially parallel to that of the first slot 8. Thedescription substantially in this case includes a deviation fromparallelism, say a few degress such as 4-10. This slot 12 extends partlytowards the bottom of the main body 4 to a distance less than that ofthe first slot 8 and, like the latter, opens out at the face of the mainbody formed by the base of the leg of the T-section. This second slotdoes not cut into the socket hole 3 but lies in a plane which touchesthe external surface of the socket part 2 of the block. Thus, when thesaid socket part 2 is mainly cylindrical on its external surface, thenthe second slot 12 would lie in a plane approximately tangential to thecylindrical exterior of the socket part 2. At the bottom of the secondslot 12 a transverse hole 13 is bored from the vertical face of the mainbody at which the two slots open, this transverse hole also cuttingthrough one wall 14 of the first slot 8, thereby forming this wall 14into a clamping tongue in the main body 4 for the aforesaid longitudinalsplitting of the socket 3.

It will be clear that by providing means for flexing the said clampingtongue 14 in a direction towards closing the first slot 8 it will causea plug (which has been inserted into the split socket 3) to be tightlygripped. For this purpose the following construction is provided. Fromthe top of the main body 4 of the plug, in the part thereof constitutingthe leg 7 of the T-section, a vertical hole 15 is bored parallel to theaxis of the socket hole 3, and this bore is in a position whereby it isintersected by the second slot 12 (see FIGURES 1, 2 and 4). This bore 15is used for a spreading device to thrust the aforesaid clamping tongue14 into its gripping position. Thus,

a clamping pin 16 (FIGURE 1) is fitted into the bore. This pin isthreaded at its inner end as at 17 so as to enter into the tapped bottomend 18 (FIGURE 4) of the bore, the threads having sufiicient clearanceto allow for misalignment, and the rest of the length of the pin isunthreaded and of larger diameter than the threaded end. A conicallytapered section 19 of the pin joins the threaded and unthreaded sectonsand co-acts with part of the bore at 20 (FIGURE 4) to flex the clampingtongue 14 when the pin is screwed as tightly as possible as possibleinto the bore. Means other than a taper on the pin 16 co-acting with ataper bore may be adopted to bring about the flexing of the clampingtongue 14 by turning a pin such as 16.

Transversely across the bottom of the block, and through the cross-bar5, 6 of the T-section, a hole 21 is drilled for the reception of alead-in wire 22 (FIG- URE 7), and one or more access holes 23(preferably two) for terminal clamping screws 24 are provided parallelto the socket hole 3 and vertically at right-angles to the saidtransverse hole 21 in the main body of the block from the top face, onein each end of the crossbar of the T-section.

With the present plug-and-socket connector the face of the socket blockcontaining the mouth of the socket will also have projecting therefromthe aforesaid clamping pin 16 readily accessible for turning so as toclamp up the plug 11 in its socket.

It has already been mentioned that the block may be disposed in variousattitudes other than vertical as illustrated in FIGURES 1-5 which wasassumed for convenience of description. In FIGURES 6 and 7 there isshown an application of the invention to an electric time switch casingwherein the socket block 1 lies at right-angles to the position shown inFIGURES 1-5, so as to expose the face containing the mouth of the sockethole 3 in a vertical plane.

Referring to FIGURES 6 and 7, there is an insulated casing 25 mouldedwith a solid block-like portion 26 in which various recesses and holesare made to suit the particular time switch and its fittings with which,except for the socket blocks 1, the invention is not concerned. Thereare two socket blocks 1 for load and line, only one of which is shown,each being inserted in a recess 27, it being understood that a secondblock 1 and its recess 27 would be in the omitted part of FIGURE 6. Theblocks are left and right handed, i.e., the unillustrated one being amirror reflection of the one shown. When the blocks 1 have beeninserted, an insulated cover plate (having holes giving access interalia to the screws 24, socket 3 for plug 11, and bore 15 for theclamping pin 16) is fixed in position on top of the insulated block 26.The latter has a channel 29 to take the cable 30 which is clamped in thebore 21 of the block 1. A hinged lid 31 is usually provided.

The plug 11, in the foregoing application to an electric time switch,will be an immovable fixture to and projecting from the time switch, theend 11a being constructed in any suitable manner for this purpose.

We claim:

An electrical plug-and-socket connection including a metal socket blockfor the reception of a plug, said block having a socket part of whichone face contains a socket hole extending from said face only partlythrough the socket part, and a main body integrally extending from saidsocket part and having a face coplanar with the aforesaid facecontaining the socket hole and an end face at right-angles thereto, saidmain body containing a first slot lying in a plane substantiallyparallel to the axis of said hole cutting into the latter and openingout at the said co-planar face of the said body and also at theright-angular face to form a longitudinally split socket, a second slotin said main body not cutting into the socket hole and lyingsubstantially parallel with the first slot, thereby forming a clampingtongue in the main body, both slots extending only partly through themain body, in combination with a bore in said main body parallel to theaxis of the socket hole, and intersected by the second slot, said borecontaining a threaded clamping pin having a conical tapered part adaptedby rotation to flex the said clamping tongue and close the socket into aplug gripping condition.

References Cited by the Examiner FOREIGN PATENTS 1,091,782 11/1954France.

EDWARD C. ALLEN, Primary Examiner.

P. TEITELBAUM, Assistant Examiner.

